Proportional representation is practised in dozens of countries from Algeria to Venezuela, and it's more established in the UK than many Britons realise. Here are 10 lessons that can be learned from examples of PR and coalition government around the world.
1. Spain and Japan demonstrate that PR does not necessarily lead to coalition government. "There is PR and there is PR," says LSE Professor Simon Hix. "You can design it to increase the chance of single-party government." Spain and Ireland elect only a limited number of MPs from each constituency, which benefits a limited number of larger parties. Germany has a threshold - 5% of the vote - which any party has to cross to be eligible for a seat. While PR in general makes coalition government more likely, both of these approaches reduce the chance of an extremely fractured parliament.
2. Germany shows that coalitions are not necessarily unstable. Early elections have only been called once since re-unification in 1990 - when Gerhard Schroeder's Red-Green coalition lost control of the upper house of parliament in 2005. Most Scandinavian countries also have stable coalitions. On the other hand, with the system used in the Netherlands and Israel (where the whole country is treated as one constituency) "you are bound to get huge fragmentation of the vote and get unwieldy coalition governments," says Professor Hix. In some other problem cases, such as Belgium, the cause may have more to do with big social and linguistic divisions in the country than the electoral system itself.
3. The UK itself already provides plenty of examples of both PR and coalition government, at the level of local government or national assemblies . One form of PR, the single transferrable vote, is used in elections to the Northern Ireland Assembly, in local government elections in Northern Ireland and Scotland, and in Northern Ireland's elections to the European Parliament. Other forms are used in elections to the Scottish Parliament, the National Assembly of Wales, the London Assembly, and in European elections in England, Scotland and Wales. "Most British citizens are also familiar with multi-member elections in many other situations, from the election of School Governors to the election of governing boards of interest groups, professional associations, trade unions, university student unions, sports clubs, and many other organisations," write Professor Hix and his co-authors in a report for the British Academy, Choosing an Electoral System. "In fact, multi-member elections may currently be the most commonly used type of election in the United Kingdom."
4. Scotland provides an example of a minority government, resulting from PR. Scotland's first two governments after devolution were Labour-Liberal Democrat coalitions. But the Scottish National Party (SNP), which emerged with most seats from the 2007 election, failed to reach a coalition deal with the Liberal Democrats and opted to form a minority government. This means it needs the backing of other political forces in the parliament for any legislative initiative - it is often forced to compromise. Is government by compromise good or bad? "It might be a new experience for you in the UK," says Professor Gert-Joachim Glaessner, of Humboldt University in Berlin. "But for other people its normal." Professor Hix notes that coalition governments tend to be less decisive than single-party governments but their policies are often closer to the views of the average citizen.
5. The Netherlands shows that it can take time to piece together a coalition government. It took the Dutch three months in 2007, and four months in 2003. While the talks continue, the old government continues in a caretaker capacity - whether or not it has a majority in the new parliament. "It's paralysis in the sense that there are no major initiatives being adopted," says the former chairman of the Dutch Labour Party, Michiel Van Hulten. "Other people might refer to it as a period of calm and quiet." During these periods the idea is occasionally raised of adopting a different electoral system. However, Michiel Van Hulten adds, "Very few people advocate a first-past-the-post system. They quickly conclude there is a danger of creating one-party rule, and excluding the vast majority of voters."
6. The Netherlands also shows how PR can help non-mainstream parties get seats. The Green Left party has had seats in parliament since 1989. In recent years, anti-immigration parties have also made inroads. Similarly, in the UK, PR could help the British National Party win a couple of seats, says Professor Hix. Michiel Van Hulten argues that this is not necessarily a bad thing. "Most people in Holland would say it's better to have these issues debated in parliament, rather than have them growing outside, disconnected from politics." Some parties don't last long in parliament, he adds. They are elected, they are exposed for what they are, and people don't vote for them four years later.
7. Australia, Fiji and Papua New Guinea are the only three countries using the Alternative Vote (AV) system favoured by the Labour Party in the UK. This is similar to a first-past-the-post system, in that one MP is elected from each constituency. The difference is that voters' second and third (and so on) choices also have an impact, ensuring that the winning candidate has broad support within the constituency. In Professor Hix's view, it does not count as a "proportional" voting system - there is no stronger connection between a party's share of the vote and its share of seats in parliament than there is with a standard first-past-the-post sytem. Sometimes the result is even less proportional, he says.
8. Japan illustrates one problem with some PR systems, and a way of fixing it. The problem is that multi-member constituencies weaken the bond between voter and elected representatives, and therefore the accountability of the MP. It's the same with European Union elections in the UK, where voters can often be heard complaining: "I do not know who my MEP is." In fact they have several MEPs, elected from a regional constituency that covers a large region of the country. The solution adopted by Japan (also used in elections to the Scottish Parliament, the National Assembly of Wales and the London Assembly) was to move to a mixed system, where some members of parliament are elected in single-member constituencies, and others are elected by PR. Germany is another country that uses a mixed system. Professor Glaessner says it's popular with voters, who often pick a constituency MP from one party, and cast a vote for a different party in the PR vote - often a smaller party whose candidate might be unlikely to succeed at constituency level.
9. Canada shows that even when a country has a first-past-the-post system, there is no guarantee that this will result in a majority government. Professor Hix and the other authors of the British Academy report, Choosing an Electoral System, point out that the two main long-term voting trends in the UK could ultimately leave the UK in the same position. These trends are declining support for the two main parties, and different voting patterns in different regions of the country.
10. Sweden currently provides an example of a country where the dominant party in the governing coalition is not the biggest in the parliament. Prime Minister Fredrik Reinfeldt represents the second largest party in parliament, and governs in a coalition with three other centre-right parties. The Society for Electoral Reform cites numerous examples where the same has occurred in local government in the UK, including Leeds, St Helens, Carlisle, Ipswich, Newport, Allerdale, Wirral, Colchester, Broxtowe and East Dunbartonshire.